Multi bin vehicle for an automated storage and retrieval system comprising a three dimensional grid

ABSTRACT

A container-handling vehicle for picking up storage containers from a three-dimensional grid of an underlying storage system includes a first set of wheels arranged at opposite sides of a vehicle body, for moving the vehicle along a first direction on the grid; a second set of wheels arranged at opposite sides of the vehicle body, for moving the vehicle along a second direction on the grid, the second direction being perpendicular to the first direction; and the first set of wheels displaceable in a vertical direction between a first position, wherein the first set of wheels allow movement of the vehicle along the first direction, and a second position, wherein the second set of wheels allow movement of the vehicle along the second direction. The vehicle body surrounds a cavity within which at least a first lifting device and a second lifting device are positioned adjacent to each other, each lifting device is arranged to lift a storage container from the grid and into the cavity, such that a bottom of the storage container is at a level above the lowest level of the second set of wheels.

TECHNICAL FIELD

The present invention relates to automated storage systems, acontainer-handling vehicle for use in such storage systems, as well asmethods for use of the container-handling vehicle in such storagesystems.

BACKGROUND

The Applicant's already known AutoStore system is a storage systemcomprising a three-dimensional storage grid structure wherein storagecontainers/containers are stacked on top of each other to a certainheight. Such a prior art system is shown in FIG. 1 . The storage systemis disclosed in detail in for instance NO317366 and WO 2014/090684 A1.

FIG. 1 discloses a framework structure of a typical prior art automatedstorage and retrieval system 1 and FIGS. 2 a and 2 b disclose knowncontainer-handling vehicles of such a system.

The framework structure comprises a plurality of uprightmembers/profiles 2 and a plurality of horizontal members 3, which aresupported by the upright members 2. The members 2, 3 may typically bemade of metal, e.g. extruded aluminium profiles.

The framework structure defines a storage grid 4 comprising multiplegrid columns 12 arranged in rows. A majority of the grid columns 12 arestorage columns 5 in which storage containers 6, also known ascontainers, are stacked one on top of another to form stacks 7. Eachstorage container 6 (or container for short) may typically hold aplurality of product items (not shown), and the product items within astorage container 6 may be identical, or may be of different producttypes, depending on the application. The framework structure guardsagainst horizontal movement of the stacks 7 of storage containers 6, andguides vertical movement of the containers 6, but does normally nototherwise support the storage containers 6 when stacked.

A horizontal rail system 8 is arranged in a grid pattern across the topof the grid columns 12, on which rail system 8 a plurality ofcontainer-handling vehicles 9 are operated to raise storage containers 6from and lower storage containers 6 into the storage columns 5, and alsoto transport the storage containers 6 above the storage columns 5. Therail system 8 comprises a first set of parallel rails 10 arranged toguide movement of the container-handling vehicles 9 in a first directionX across the top of the frame structure 1, and a second set of parallelrails 11 arranged perpendicular to the first set of rails 10 to guidemovement of the container-handling vehicles 9 in a second direction Y,which is perpendicular to the first direction X, see FIG. 3 . In thisway, the rail system 8 defines an upper end of the storage columns 5,above which the container-handling vehicles 9 can move laterally abovethe storage columns 5, i.e. in a plane, which is parallel to thehorizontal X-Y plane.

Each container-handling vehicle 9 comprises a vehicle body 13 and firstand second sets of wheels 14, 15 which enable the lateral movement ofthe container-handling vehicle 9, i.e. the movement in the X and Ydirections. In FIG. 2 , two wheels in each set are visible. The firstset of wheels 14 is arranged to engage with two adjacent rails of thefirst set 10 of rails, and the second set of wheels 15 arranged toengage with two adjacent rails of the second set 11 of rails. One of theset of wheels 14, 15 can be lifted and lowered, so that the first set ofwheels 14 and/or the second set of wheels 15 can be engaged with theirrespective set of rails 10, 11 at any one time.

Each container-handling vehicle 9 also comprises a lifting device 18(not shown in FIGS. 1 and 2 a, but visible in FIG. 2 b ) for verticaltransportation of storage containers 6, e.g. raising a storage container6 from and lowering a storage container 6 into a storage column 5. Thelifting device 18 comprises a lifting frame (not shown in FIG. 2 a , butsimilar to the one shown in FIG. 2 b labelled 17) which is adapted toengage a storage container 6, which lifting frame can be lowered fromthe vehicle body 13 so that the position of the lifting frame withrespect to the vehicle body 13 can be adjusted in a third direction Z,which is orthogonal the first direction X and the second direction Y.

Conventionally, and for the purpose of this application, Z=1 identifiesthe uppermost layer of the grid 4, i.e. the layer immediately below therail system 8 (in the present application, the rail system 8 is termedthe top level of the grid), Z=2 is the second layer below the railsystem 8, Z=3 is the third layer etc. In the embodiment disclosed inFIG. 1 , Z=8 identifies the lowermost, bottom layer of the grid 4.Consequently, as an example and using the Cartesian coordinate system X,Y, Z indicated in FIG. 1 , the storage container identified as 6′ inFIG. 1 can be said to occupy grid location or cell X=10, Y=2, Z=3. Thecontainer-handling vehicles 9 can be said to travel in layer Z=0 andeach grid column 12 can be identified by its X and Y coordinates.

Each container-handling vehicle 9 comprises a storage compartment orspace for receiving and stowing a storage container 6 when transportingthe storage container 6 across the grid 4. The storage space maycomprise a cavity 21 arranged centrally within the vehicle body 13, e.g.as is described in WO2014/090684A1, the contents of which areincorporated herein by reference, and as shown in FIG. 2 a.

Alternatively, the container-handling vehicles may have a cantileverconstruction, as is described in NO317366, the contents of which arealso incorporated herein by reference, and as shown in FIG. 2 b.

The container-handling vehicles 9 may have a footprint F, i.e. ahorizontal periphery in the X and Y directions (see FIG. 4 ), which isgenerally equal to the lateral or horizontal extent of the rails, seeFIG. 4 , surrounding the open end of a single grid column 12, i.e.slightly larger than the periphery/circumference of a grid column 12 inthe X and Y directions, e.g. as described in WO2015/193278A1, thecontents of which are incorporated herein by reference. Alternatively,the container-handling vehicles 9 may have a footprint which is largerthan the lateral extent of the rails surrounding a single grid column12, e.g. as disclosed in WO2014/090684A1.

The rail system 8 may be a single-track system, as shown in FIG. 3 .Preferably, the rail system 8 is a double-track system, as shown in FIG.4 , thus allowing a container-handling vehicle 9 having a footprint Fgenerally corresponding to the rails surrounding a grid column 12 totravel along a row of grid columns in either an X or Y direction even ifanother container-handling vehicle 9 is positioned above a grid column12 adjacent to that row.

In a storage grid, a majority of the grid columns 12 are storage columns5, i.e. grid columns where storage containers are stored in stacks.However, a grid normally has at least one grid column 12 which is usednot for storing storage containers, but which comprises a location wherethe container-handling vehicles can drop off and/or pick up storagecontainers so that they can be transported to an access station wherethe storage containers 6 can be accessed from outside of the grid ortransferred out of or into the grid, i.e. a container handling station.Within the art, such a location is normally referred to as a “port” andthe grid column in which the port is located may be referred to as aport column.

The grid 4 in FIG. 1 comprises two port columns 19 and 20. The firstport column 19 may for example be a dedicated drop-off port column wherethe container-handling vehicles 9 can drop off storage containers to betransported to an access or a transfer station (not shown), and thesecond port 20 column may be a dedicated pick-up port column where thecontainer-handling vehicles 9 can pick up storage containers that havebeen transported to the grid 4 from an access or a transfer station.

When a storage container 6 stored in the grid 4 disclosed in FIG. 1 isto be accessed, one of the container-handling vehicles 9 is instructedto retrieve the target storage container from its position in the grid 4and transport it to the drop-off port 19. This operation involves movingthe container-handling vehicle 9 to a grid location above the storagecolumn 5 in which the target storage container is positioned, retrievingthe storage container 6 from the storage column 5 using thecontainer-handling vehicle's lifting device (not shown in the prior artcentral cavity robot shown in FIG. 2 a , but normally similar to thelifting device 18 of the prior art vehicle of FIG. 2 b ), andtransporting the storage container to the drop-off port 19. The priorart vehicle 9 shown in FIG. 2 b better illustrates the general design ofthe lifting device. Details of this prior art vehicle 9 (often referredto as a cantilever robot) are described in the Norwegian patentNO317366. The lifting devices 18 of both prior art vehicles 9 comprise aset of lifting bands 16 connected close to the corners of a liftingframe 17 (may also be termed a gripping device) for releasableconnection to a storage container. To raise or lower the lifting frame17 (and optionally a connected storage container 6), the lifting bands16 are spooled on/off at least one rotating lifting shaft or drum (notshown) arranged in the container-handling vehicle. Various designs ofthe at least one lifting shaft are described in for instanceWO2015/193278 A1 and WO2017/129384 A1. The lifting frame 17 featurescontainer connecting elements 24 for releasably connecting to a storagecontainer, and guiding pins 30. If the target storage container islocated deep within a stack 7, i.e. with one or a plurality of otherstorage containers positioned above the target storage container, theoperation also involves temporarily moving the above-positioned storagecontainers prior to lifting the target storage container from thestorage column. This step, which is sometimes referred to as “digging”within the art, may be performed with the same container-handlingvehicle that is subsequently used for transporting the target storagecontainer to the drop-off port 19, or with one or a plurality of othercooperating container-handling vehicles. Alternatively, or in addition,the automated storage and retrieval system may have container-handlingvehicles specifically dedicated to the task of temporarily removingstorage containers from a storage column. Once the target storagecontainer has been removed from the storage column, the temporarilyremoved storage containers can be repositioned into the original storagecolumn. However, the removed storage containers may alternatively berelocated to other storage columns.

When a storage container 6 is to be stored in the grid 4, one of thecontainer-handling vehicles 9 is instructed to pick up the storagecontainer from the pick-up port 20 and transport it to a grid locationabove the storage column 5 where it is to be stored. After any storagecontainers positioned at or above the target position within the storagecolumn stack have been removed, the container-handling vehicle 9positions the storage container at the desired position. The removedstorage containers may then be lowered back into the storage column, orrelocated to other storage columns.

For monitoring and controlling the automated storage and retrievalsystem, e.g. monitoring and controlling the location of respectivestorage containers within the grid 4, the content of each storagecontainer 6 and the movement of the container-handling vehicles 9 sothat a desired storage container can be delivered to the desiredlocation at the desired time without the container-handling vehicles 9colliding with each other, the automated storage and retrieval systemcomprises a control system, which typically is computerised andcomprises a database for keeping track of the storage containers.

The prior art container-handling vehicles 9 described above may handleand transport only one container 6 in each operation, thereby setting alimitation on the efficiency of certain operations performed by thestorage system, including retrieval and/or storage of multiple storagecontainers and “digging”.

A container-handling vehicle able to retrieve multiple storagecontainers from the same storage column is disclosed in WO2013167907.However, the disclosed container-handling vehicle suffers from lowstability putting restrictions on its speed and acceleration.

In view of the above, it is desirable to provide a more efficientcontainer-handling vehicle, an automated storage and retrieval systemcomprising said container-handling vehicle, and a method for operatingsuch a system. In particular, the present invention provides acontainer-handling vehicle having an improved operational speed invarious situations relative the prior art vehicles.

SUMMARY OF THE INVENTION

The present invention is defined in the attached claims and in thefollowing:

In a first aspect, the present invention provides a container-handlingvehicle for picking up storage containers from a three-dimensional gridof an underlying storage system, comprising

-   -   a first set of wheels arranged at opposite sides of a vehicle        body, for moving the vehicle along a first direction (i.e. a        first horizontal direction) on the grid;    -   a second set of wheels arranged at opposite sides of the vehicle        body, for moving the vehicle along a second direction (i.e. a        second horizontal direction) on the grid, the second direction        being perpendicular to the first direction; and    -   the first set of wheels displaceable in a vertical direction        between a first position, wherein the first set of wheels allow        movement of the vehicle along the first direction, and a second        position, wherein the second set of wheels allow movement of the        vehicle along the second direction, wherein        the vehicle body surrounds a cavity within which at least a        first lifting device and a second lifting device are positioned        adjacent to each other, each lifting device is independently        controlled and arranged to lift a storage container from the        grid and into the cavity, such that a bottom of the storage        container is at a level above the lowest level of the second set        of wheels. Each lifting device is also able to lower a storage        container from the cavity and into the grid.

The first and the second lifting devices are adjacent such that thecontainer-handling vehicle may accommodate two adjacent storagecontainers within the cavity.

When the first lifting device and the second lifting device areindependently controlled, the first lifting device is controlledindependently of the second lifting device. That is, one of the liftingdevices may independently perform an operation, for instance lifting astorage container from a first storage column, while the other liftingdevice is performing another or similar operation, for instancereturning a storage container to a second storage column adjacent to thefirst storage column.

In an embodiment of the container-handling vehicle, the first liftingdevice and the second lifting device is connected to at least one firstrotatable lifting shaft (or a first set of lifting shafts) and at leastone second rotatable lifting shaft (or a second set of lifting shafts),respectively. The lifting shafts are arranged at an upper level withinthe vehicle, i.e. at a level above the cavity or at an upper levelwithin the cavity. Each lifting device is connected to the correspondinglifting shaft(s) via a set of lifting bands, or alternatively, comprisesa set of lifting bands connected to the corresponding lifting shaft(s).The rotation of each lifting shaft, or set of lifting shafts, isindependently controlled, such that the connected lifting device may beraised or lowered independent of the other lifting devices.

In an embodiment of the container-handling vehicle, each of the at leastfirst lifting device and second lifting device comprises a lifting framefor releasably connecting to a container. The lifting frames of the atleast first lifting device and second lifting device are adjacent.

In one embodiment, the container-handling vehicle comprises a thirdlifting device arranged adjacent to the first or the second liftingdevice. The third lifting device may advantageously comprise any of thefeatures disclosed for the first and second lifting device, e.g. beingconnected to at least one third rotatable lifting shaft and comprising alifting frame.

In one embodiment, the container-handling vehicle comprises a fourthlifting device arranged adjacent to the third lifting devices and thefirst or the second lifting device. The fourth lifting device mayadvantageously comprise any of the features disclosed for the first andsecond lifting device, e.g. being connected to at least one fourthrotatable lifting shaft and comprising a lifting frame.

In one embodiment, the container-handling device comprises multipleadjacent rows of lifting devices, each row comprising at least twoadjacent lifting devices, i.e. at least a first and a second liftingdevice, and each lifting device comprising any of the features disclosedfor the first and second lifting device, e.g. each being connected to atleast one rotatable lifting shaft and comprising a lifting frame. Eachlifting device is controlled independently of the other liftingdevice(s). In one embodiment, a first row may comprise at least a firstand second lifting device, and a second adjacent row may comprise atleast a third and second lifting device, such that the first liftingdevice is adjacent the third lifting device and the second liftingdevice is adjacent the fourth lifting device.

In one embodiment, the container-handling vehicle comprises a supportbeam connecting two opposite sides of a framework of the vehicle body,the support beam arranged in a horizontal position between two adjacentlifting devices or between two rows of lifting devices. The support beamis preferably arranged at a level above the lowermost level of thesecond set of wheels (or above the opening of the cavity) and below thelevel of the lifting devices when fully retracted into the cavity. Thewidth of the support beam is smaller than, or equal to, the horizontaldistance separating two adjacent lifting devices (alternativelyseparating the lifting frames of two adjacent lifting devices) orseparating two adjacent rows of lifting devices (or alternativelyseparating the lifting frames of two adjacent rows of lifting devices).

In one embodiment, the container-handling vehicle comprises at least onevertical frame guiding element (or frame guide) arranged inside thecavity. The frame guide extends between the adjacent lifting frames. Inother words, the frame guide is arranged between the lifting frames ofthe at least first and second lifting device (i.e. the vertical frameguide is arranged between any adjacent lifting frames). The verticalframe guide is arranged such that lateral movement of the liftingframes, and consequently the lateral movement of any storage containersconnected to the lifting frames, is restricted when entering the cavityand/or when inside the cavity. The frame guide may comprise at least onelongitudinal plate or rib element arranged inside the cavity andextending at least partly between two adjacent lifting frames. Thelongitudinal plate or rib element may preferably extend in a verticaldirection from a position at a lower level of the cavity, for instanceat, or above, the level of the cavity opening, to a position at a levelcorresponding to, or above, an uppermost level of the lifting frame wheninside the cavity. The frame guiding element(s) separates the cavityinto multiple sections, each section sized to accommodate a storagecontainer. The frame guiding element may be a part, preferably anintegral part, of a framework of the vehicle body.

In a second aspect, the present invention provides an automated storageand retrieval system comprising a three-dimensional grid and at leastone container-handling vehicle according to the first aspect, whereinthe grid comprises multiple storage columns, in which storage containersmay be stored on top of one another in vertical stacks, and a portcolumn for receiving and transporting a storage container to an accessstation; and the container handling vehicle is operated on rails at atop level of the grid for retrieving storage containers from, andstoring storage containers in, the storage columns, and for transportingthe storage containers horizontally across the grid; wherein the firstlifting device and the second lifting device are arranged such thattheir respective lifting frames may enter two adjacent storage columnsat the same time. In other words, the respective lifting frames may becentered relative to two adjacent storage columns at the same time.

In an embodiment of the automated storage and retrieval system, the atleast one container-handling device comprises a third and a fourthlifting device, the third and the fourth lifting device are arrangedsuch that their respective lifting frames may enter two adjacent storagecolumns at the same time. In other words, the respective lifting framesmay be centered relative to two adjacent storage columns at the sametime. Each of the lifting frames of the third and fourth lifting deviceis preferably arranged to enter a storage column adjacent to one of thestorage columns into which the lifting frame of the first or the secondlifting device may enter

In an embodiment of the automated storage and retrieval system, thelifting frames of the first lifting device and the second liftingdevice, i.e. the lifting frames of any two adjacent lifting devices, arehorizontally separated by a distance being larger than, or equal to, thewidth of the rails separating two adjacent storage columns. That is, therespective lifting frames are separated by a distance which allows themto enter two adjacent storage columns at the same time.

In an embodiment of the automated storage and retrieval system, thecontainer-handling vehicle has a horizontal periphery equal to, or lessthan, the horizontal periphery of a set of rails or the horizontal areadelimited by the centreline of the set of rails, surrounding at leasttwo adjacent storage columns or at least two adjacent rows of storagecolumns. In a storage system comprising a dual track rail system, thehorizontal periphery of the container-handling vehicle is equal to orslightly less than the horizontal area delimited by the centreline of aset of rails surrounding two adjacent storage columns, i.e. such that asecond container-handling vehicle according to the first aspect may bearranged above any of the storage columns surrounding the two adjacentstorage columns or the at least two adjacent rows of storage columns,above which the first container handling vehicle is arranged.Preferably, each of the storage columns has a rectangular cross-section,and the horizontal periphery of the container-handling vehicle is equalto, or less than, the horizontal periphery of a set of rails surroundingat least two storage columns adjacent at their long sides. In someembodiments, the horizontal periphery of the container-handling vehicleis equal to, or less than, the horizontal periphery of a set of railssurrounding at least two storage columns adjacent at their short sides.

In yet an embodiment of the automated storage and retrieval system, thecontainer-handling vehicle has a horizontal periphery equal to, or lessthan, the horizontal periphery of a set of rails, or the horizontal areadelimited by the centreline of the set of rails, surrounding multipleadjacent rows of storage columns, each row comprising at least twoadjacent storage columns.

In an embodiment of the automated storage and retrieval system, each ofthe lifting frames comprises container connecting elements forreleasable connection to corresponding lifting frame connecting elementson a peripheral top section of the storage containers. Each liftingframe may also comprise guiding pins for ensuring a correct positioningof the container connecting elements.

In a third aspect, the present invention provides a method of retrievingat least one storage container from an automated storage and retrievalsystem. The automated storage and retrieval system may be a systemaccording to the second aspect, or may comprise a three-dimensional gridand at least one container-handling vehicle, wherein the grid comprisesmultiple storage columns, in which storage containers may be stored ontop of one another in vertical stacks, and a port column for receivingand transporting a storage container to an access station; and thecontainer handling vehicle is operated on rails at a top level of thegrid for retrieving storage containers from, and storing storagecontainers in, the storage columns, and for transporting the storagecontainers horizontally across the grid; wherein the container-handlingvehicle comprises at least a first lifting device and a second liftingdevice arranged such that they may retrieve and/or store a storagecontainer from/in at least two storage columns at the same time,preferably at least two adjacent storage columns.

The method comprises the steps of:

-   -   identifying a first storage container to be retrieved, also        denoted a target storage container;    -   moving the container-handling vehicle, such that the first        lifting device is centred relative a first storage column        comprising the first storage container;    -   retrieving a second storage container by the first lifting        device, also denoted a non-target storage container, the second        storage container arranged in the first storage column at a        level above the first storage container;    -   moving the container-handling vehicle, such that the second        lifting device is centred relative the first storage column; and    -   retrieving the first storage container by the second lifting        device.

In an embodiment of the third aspect, the method further comprises thestep of:

-   -   storing the second storage container in a second storage column        adjacent to the first storage column, preferably simultaneously        with the step of retrieving the first container; or    -   returning the second storage container to the first storage        column when the first storage container has been retrieved; or    -   storing the second storage container in a third storage column        when the first storage container has been retrieved.

In an embodiment of the third aspect, the method comprises a step ofmoving the container-handling vehicle along a pathway to the portcolumn, and optionally delivering the first storage container to theport column for transfer out of the storage system.

The third storage column may for example be arranged along the pathwayto the port column or along a pathway to a storage column containing afurther target storage container to be retrieved.

In a fourth aspect, the present invention provides a method ofretrieving at least one storage container from an automated storage andretrieval system. The automated storage and retrieval system may be asystem according to the second aspect, or may comprise athree-dimensional grid and at least one container-handling vehicle,wherein the grid comprises multiple storage columns, in which storagecontainers may be stored on top of one another in vertical stacks, and aport column for receiving and transporting a storage container to anaccess station; and the container handling vehicle is operated on railsat a top level of the grid for retrieving storage containers from, andstoring storage containers in, the storage columns, and for transportingthe storage containers horizontally across the grid; wherein thecontainer-handling vehicle comprises at least a first lifting device anda second lifting device arranged such that they may retrieve and/orstore a storage container from/in at least two storage columns at thesame time, preferably two adjacent storage columns.

The method of the fourth aspect comprises the steps of:

-   -   identifying a first storage container to be retrieved, also        denoted a target storage container;    -   moving the container-handling vehicle, such that the first        lifting device is centred relative a first storage column        comprising the first storage container;    -   retrieving a second storage container, also denoted a non-target        storage container, by the first lifting device, the second        storage container arranged in the first storage column at a        level above the first storage container;    -   moving the container-handling vehicle, such that the second        lifting device is centred relative the first storage column;    -   retrieving a further second storage container by the second        lifting device;    -   storing any one of the second storage containers in a second        storage column, preferably arranged adjacent to the first        storage column;    -   moving the container-handling vehicle, such that the first or        the second lifting device is centred relative the first storage        column; and    -   retrieving the first storage container by the first or second        lifting device;

In an embodiment of the fourth aspect, the method comprises a step ofmoving the container-handling vehicle along a pathway to the portcolumn, and optionally delivering the first storage container to theport column for transfer out of the storage system.

In a fifth aspect, the present invention provides a method of retrievingat least one storage container from an automated storage and retrievalsystem. The automated storage and retrieval system may be a systemaccording to the second aspect, or may comprise a three-dimensional gridand at least one first type and one second type of container-handlingvehicle, wherein the grid comprises multiple storage columns, in whichstorage containers may be stored on top of one another in verticalstacks, and a port column for receiving and transporting a storagecontainer to an access station; and the first and second type ofcontainer handling vehicles are operated on rails at a top level of thegrid for retrieving storage containers from, and storing storagecontainers in, the storage columns, and for transporting the storagecontainers horizontally across the grid; wherein the first type ofcontainer-handling vehicle comprises multiple lifting device arrangedsuch that they may independently retrieve and/or store a storagecontainer from/in multiple storage columns at the same time. The secondtype of container-handling vehicle may advantageously comprise a singlelifting device similar to one of the multiple lifting devices of thefirst type of container-handling vehicle.

The method of the fifth aspect comprises the steps of:

-   -   a. identifying a first storage container, also denoted a target        container, to be retrieved;    -   b. moving the first type of container-handling vehicle, such        that one of the multiple lifting devices (i.e. one of the        multiple lifting devices not currently lifting a storage        container) is centred relative a first storage column comprising        the first storage container;    -   c. retrieving a second storage container, also denoted a        non-target container, by the lifting device centred relative the        first storage column, the second storage container arranged in        the first storage column at a level above the first storage        container;    -   d. repeating steps b and c until no second storage containers,        i.e. no non-target containers, are at a level above the first        storage container; and    -   e. retrieving the first storage container by a first or second        type of container-handling vehicle.

In an embodiment of the fifth aspect, the method comprises a step ofstoring a second storage container in a storage column other than thefirst storage column. In this manner an occupied lifting device is freedto retrieve a further second storage container from the first storagecolumn. If the storage column is arranged adjacent to the first storagecolumn, the step is preferably performed simultaneously to step c.

In one embodiment of the fifth aspect, the method comprises a step,following step d, of moving the first type of vehicle away from thefirst storage column to provide one of the second type ofcontainer-handling vehicles access to the first storage container toperform step e.

In an embodiment of the fifth aspect, the second type ofcontainer-handling vehicle comprises a single lifting device and isarranged to retrieve and transport the first storage container to adesired location, such as a port column or buffer zone. The second typeof container-handling vehicle may for example be a prior art vehicle asillustrated in FIG. 2 a or 2 b.

SHORT DESCRIPTION OF THE DRAWINGS

Certain embodiments of the present invention will now be described indetail by way of example only and with reference to the followingdrawings:

FIG. 1 is a perspective side view of a prior art storage and retrievalsystem.

FIGS. 2 a and 2 b depict two different prior art container handlingvehicles.

FIGS. 3 and 4 are top side schematic views of two types of rail systemsfor use in the storage system in FIG. 1 .

FIG. 5 is a perspective side view of a first exemplary embodiment of acontainer-handling vehicle according to the invention.

FIG. 6 is a side view of the container-handling vehicle in FIG. 5 .

FIG. 7 is a side view of the container-handling vehicle in FIG. 5 .

FIG. 8 is a cross-sectional view of the container-handling vehicle inFIG. 6 along A-A.

FIG. 9 is a perspective side view of the container-handling vehicle inFIG. 5 , wherein the lifting devices extend out of the cavity.

FIG. 10 is a side view of the container-handling vehicle in FIG. 9 .

FIG. 11 is a perspective side view of a second exemplary embodiment of acontainer-handling vehicle according to the invention.

FIG. 12 is a perspective side view of the container-handling vehicle inFIG. 11 , wherein the external panels are removed.

FIG. 13 is a perspective view of the container-handling vehicle in FIG.11 , shown from below.

FIG. 14 shows the container-handling vehicle in FIG. 13 , wherein thelifting frames are lowered.

FIG. 15 shows the container-handling vehicle in FIG. 11 , wherein thelifting frames are lowered.

FIG. 16 is a perspective side view of a third exemplary embodiment of acontainer-handling vehicle according to the invention.

In the drawings, like reference numbers have been used to indicate likeparts, elements or features unless otherwise explicitly stated orimplicitly understood from the context.

DETAILED DESCRIPTION OF THE INVENTION

In the following, embodiments of the invention will be discussed in moredetail by way of example only and with reference to the appendeddrawings. It should be understood, however, that the drawings are notintended to limit the invention to the subject-matter depicted in thedrawings.

As mentioned above, a disadvantage of prior art container-handlingvehicles 9, see FIGS. 2 a and 2 b , is their ability to handle only onecontainer 6 at a time.

A first exemplary embodiment of a container-handling vehicle 27 aaccording to the invention is shown in FIGS. 5-10 . The inventivevehicle features a first set of wheels 14 arranged at opposite sides ofa vehicle body 13, for moving the vehicle 27 a on a rail system 8 alonga first direction X on a grid 4 of a storage system 1, and a second setof wheels 15 arranged at opposite sides of the vehicle body 13, formoving the vehicle 27 a along a second direction Y on the grid 4. Thesecond direction Y is perpendicular to the first direction X. The firstset of wheels 14 is displaceable in a vertical direction Z between afirst position and a second position by being connected to a wheeldisplacement assembly 28 (not shown, see FIGS. 12 and 16 ). In the firstposition, the first set of wheels 14 is at a level below the second setof wheels 15 and in contact with the rail system, such that movement ofthe vehicle 27 a along the first direction X is allowed, and in thesecond position the first set of wheels are vertically displaced awayfrom the rail system to a level above the second set of wheels 15, suchthat the second set of wheels 15 is in contact with the rail systemallowing movement of the vehicle 27 a along the second direction Y.Structural details of suitable assemblies for providing displaceablesets of wheels are disclosed in for instance WO2015/193278 A1 andWO2017/153583, the contents of which are incorporated by reference, aswell as in the second and third exemplary embodiments shown in FIGS.11-16 .

The vehicle body 13 surrounds a cavity 21 within which a first liftingdevice 18 a and a second lifting device 18 b are positioned adjacent toeach other; the cavity being open at its underside to allow access frombelow. Each lifting device is arranged to lift a storage container 6from the grid 4 of an underlying storage system 1 and into the cavity21, and vice versa. By having two lifting devices arranged adjacent toeach other, the inventive vehicle 27 a may accommodate two adjacentstorage containers within the cavity 21. When accommodated in thecavity, the bottom of each storage container is at a level above thelowest level of the second set of wheels 15. By being arranged above thelowest level of the second set of wheels 15, the bottom of the storagecontainers 6 will not interfere with the rail system 10,11 of the grid 4during horizontal movement of the container-handling vehicle, see FIGS.1, 3 and 4 .

Each of the first and second lifting device comprises a lifting frame 17a,17 b connected to a corresponding rotatable lifting shaft 22 a,22 bvia a set of lifting bands 16 a,16 b, see FIGS. 8-10 . The lifting frame17 a,17 b is provided with container connecting elements 24 forreleasable connection to a storage container 6 and a guiding pin 30 ateach corner of the lifting frame for ensuring a correct positioning ofthe container connecting elements 24 relative the storage container.

The rotatable lifting shafts 22 a,22 b are arranged above the cavity 21at an internal upper level of the vehicle body 13. In all embodimentsdisclosed in the present specification, each of the lifting devices isconnected, via four lifting bands, to a single corresponding liftingshaft. This particular design is advantageous in that few separate partsare required and it occupies a minimum of space providing a highlycompact and light lifting shaft assembly. Although not as advantageousas the disclosed lifting shaft assembly, the inventivecontainer-handling vehicles disclosed herein may alternatively compriseany other suitable lifting shaft assembly. Various suitable designs ofrotatable lifting shafts and lifting shaft assemblies, and theirconnection to drive assemblies for providing rotation, as well as theirconnection to lifting bands are disclosed in for instance WO2015193278A1 and WO2017129384 A1, the contents of which are incorporated byreference. In an alternative embodiment, the rotatable lifting shaftsmay for instance be driven by a common motor connecting the two shaftsby a clutch arrangement allowing independent rotational control of thetwo lifting shafts.

Thus, the container-handling vehicle 27 a of the present inventioncomprises two adjacent lifting devices 18 a,18 b allowing for thesimultaneous accommodation of two storage containers within the cavity21. The lifting frames 17 a, 17 b of the two lifting devices arehorizontally separated by a distance D (see FIG. 10 ) being equal orlarger than the width W of the rails system 10,11 arranged at the topend of the storage columns 5, see FIGS. 3, 4 and 8 . In other words, thelifting devices 18 a,18 b are spaced such that the container-handlingvehicle 27 a may be arranged above two adjacent storage columns 5 whilehaving one of the lifting frames 17 a,17 b centered relative to each ofsaid storage columns.

By having two adjacent lifting devices, the container-handling vehicle27 a according to the invention provides an improved operational speedin various situations relative a prior art vehicle 9.

Several specific, but common, situations, wherein the container-handlingvehicle 27 a provides an improved operational speed or efficiency to thestorage system are described below.

In an automated storage system 1, storage containers 6 containinghigh-turnover goods (in the following termed HT-containers) are oftenarranged at one of the uppermost levels of the storage columns 5 toincrease the efficiency of the system. That is, HT-containers areusually arranged in the first or second layer (Z=1 or 2) of the grid 4,see FIG. 1 and description above.

For instance, due to the high turnover of the goods in theHT-containers, several HT-containers arranged in the first layer areoften to be retrieved from the storage system at the same time. When twoof these HT-containers are arranged in neighboring or closely positionedstorage columns 5, the inventive container-handling vehicle 27 a mayretrieve both HT-containers before they are delivered to the port column19. The efficiency of such an operation is greatly increased compared toa single prior art container-handling vehicle 9, which is required tomove back and forth between the port column 19 for each HT-container tobe retrieved. The same situation applies to HT-containers when returnedto the storage columns.

In situations where the HT-container (or a first storage container) tobe retrieved is arranged in the second layer, i.e. below a non-targetcontainer (or a second storage container), the efficiency may beimproved even further. In such situations, the container-handlingvehicle 27 a may retrieve the non-target container arranged above theHT-container by use of the first lifting device 18 a before retrievingthe HT-container by use of the second lifting device 18 b. Depending onwhich action is determined to be most efficient by a storage controlsystem, the non-target container may be returned to the same storagecolumn from which it was retrieved after retrieval of the HT-container,returned to (or stored in) an adjacent storage column whilesimultaneously retrieving the HT-container, returned to a suitablestorage column during transport of the HT-container to the port column19, or accommodated in the container-handling vehicle 27 a while theHT-container is delivered to the port column 19.

Based on the description above, it follows that storage containers 6containing low-turnover goods (in the following termed LT-containers)are often stored at the lower levels of a storage column. To retrieveLT-containers it is normally necessary to remove multiple storagecontainers (i.e. non-target containers) arranged above a targetedLT-container (i.e. a target container) before the LT-container may beretrieved. The container-handling vehicle 27 a of the first exemplaryembodiment is highly efficient in removing multiple non-targetcontainers to allow access to the LT-container.

A second exemplary embodiment of a container-handling vehicle 27 baccording to the invention is shown in FIGS. 11-15 .

The container-handling vehicle 27 b in FIGS. 11-15 is particularlysuited for removing multiple storage containers 6 (i.e. non-targetcontainers) arranged above a target container stored at a lower level ofa storage column, i.e. performing a digging operation. Consequently, thevehicle 27 b is in the following referred to as a digger. The cavity ofthe digger features four separate lifting devices 17 a-17 d forindependently lifting/lowering a total of four storage containers 6.Each of the lifting devices has the same features as described above forthe first exemplary container-handling vehicle 27 a. It should beunderstood that any number of separate lifting devices of such a diggeris possible. In other exemplary embodiments of the digger there may be3×2 lifting devices (i.e. two adjacent rows of 3 adjacent liftingdevices), 4×2 lifting devices, 3×3 lifting devices or 4×4 liftingdevices. To obtain a higher structural stability of the digger body 13,a support beam 25 may connect two opposite sides at the lower opening ofthe cavity as shown in FIG. 13 . Such a support beam 25 should have awidth smaller than the distance D separating two adjacent liftingframes.

The digger 27 b comprises a vertical frame guiding element 23 (i.e. aframe guide) arranged within the cavity 21. At least parts of the frameguiding element 23 is arranged between the lifting frames 17 a-17 d andrestricts the lateral movement of the lifting frames and any storagecontainer connected thereto. Restricting the lateral movement of thelifting frames are particularly important in a container-handlingvehicle in which the lifting frames are independently controlled.Without the guiding element 23, adjacent lifting frames would have asubstantial risk of interfering with each other during operation,especially when moving in opposite directions, i.e. when one liftingframe (e.g. 17 a) is lifted and an adjacent lifting frame (i.e. 17 b or17 d) is lowered. In addition to minimizing the risk of interferencebetween adjacent lifting frames, the guiding element also increases thestability of the vehicle by restricting lateral movement of storagecontainers inside the cavity during acceleration of the vehicle. In thisparticular embodiment, the frame guiding element 23 is a longitudinalprofile/beam having a substantially cross-shaped cross-section. Theprofile is at one end connected to an upper level of the cavity and theother end to the support beam. In this example, the frame guidingelement is an integral part of the framework of the vehicle body. Bybeing part of the framework, the frame guiding element also provides anincreased structural stability to the vehicle body.

It is noted that the first exemplary embodiment 27 a in FIGS. 5-10 isdepicted without a frame guiding element 23. However, anycontainer-handling vehicle according to the invention comprising morethan two lifting devices, e.g. two adjacent lifting devices 17 a, 17 b,may advantageously comprise a vertical frame guiding element restrictingthe lateral movement of the lifting frames as discussed for the digger.

When used in a storage system as described above, the digger 27 b maysequentially retrieve multiple non-target containers 6 from a storagecolumn 5 (see FIG. 1 ) by performing the following steps when anLT-container (also termed a target container or first storage container)to be retrieved has been identified/selected:

In a first step, the digger is moved, such that one of the four liftingdevices not currently lifting a storage container is centered relative afirst storage column comprising the LT-container; and

in a second step, a non-target container is retrieved/lifted by thelifting device centered relative the first storage column, thenon-target container is arranged in the first storage column at a levelabove the LT-container.

The first and second step is then repeated until no non-targetcontainers are at a level above the LT-container.

In case the number of non-target containers exceeds the number oflifting devices of the digger, i.e. more than four non-target containersin this particular example, the digger may perform a further step ofstoring a non-target container in a storage column other than the firststorage column. To obtain an optimal efficiency the further step ispreferably performed in a storage column adjacent to the first storagecolumn and simultaneously with the second step.

When the LT-container is the uppermost container in the first storagecolumn, that is, all non-target containers arranged above theLT-container have been removed, the LT-container may preferably beretrieved by another type of container-handling vehicle (i.e. a secondtype of container-handling vehicle) more suited for transporting theLT-container to for instance a port column of the storage system. Thesecond type of container-handling vehicle may for instance be a priorart container-handling vehicle 9′ as described above or similar.

A third exemplary embodiment of a container-handling vehicle 27 caccording to the invention is shown in FIG. 16 . The vehicle issubstantially similar to the first embodiment, but differs in that itfeatures a frame guiding element (alternatively termed a frame guidingassembly) comprising multiple vertical longitudinal plates 23(alternatively ribs). The plates/ribs 23 are arranged on/at an internalside section of the cavity, in this example on two opposing internalside sections, and extend at least partly between the two liftingframes. In this example, similar to the second embodiment, the frameguiding element is an integral part of the framework of the vehiclebody. By being part of the framework, the frame guiding element alsoprovides an increased structural stability to the vehicle body. Afurther differentiating feature of the third embodiment is that thesecond set of wheels 15 comprises three wheels, as opposed to two wheelsin the first embodiment.

As disclosed above, both the second and the third embodiment featuresvertical frame guiding elements forming a part of the framework of thevehicle body. Although having the frame guiding element as a part of theframework provides an advantageous effect, i.e. providing increasedstructural stability, it is not a requirement.

In the first exemplary embodiment, the container-handling vehicle 27 afeatures a cavity within which two rectangular storage containers may beaccommodated having a long side of one storage containers adjacent toone of the long sides of the other. In other words, the lifting framesare rectangular, each frame having a first and second parallel andopposite sides. The first sides being longer than the second sides, anda first side of the first lifting frame is arranged adjacent to a firstside of the second lifting frame. This is a preferred embodiment for avehicle comprising only two lifting devices, or a vehicle comprising amultiple number of lifting devices arranged in line (X or Y direction),as this configuration makes it compatible with most prior art portcolumns 19 or storage container lifts (lifts for transporting containersinto and out of a storage system). However, in other embodimentsfeaturing only two lifting devices, or multiple number of liftingdevices arranged in line, the cavity and lifting devices may be arrangedsuch that the storage containers are arranged adjacent along their shortsides.

REFERENCE NUMBERS

-   1 Framework structure/underlying storage system-   2 Upright members/profiles-   3 Horizontal members-   4 Storage grid-   5 Storage column-   6 Storage container-   7 Stacks-   8 Rail system-   9 Prior art container-handling vehicle-   10 First set of parallel rails-   11 Second set of parallel rails-   12 Grid column-   13 Vehicle body-   14 First set of wheels-   15 Second set of wheels-   16 Lifting bands-   17 Lifting frame-   18 Lifting device-   19 First port column-   20 Second port column-   21 Cavity-   22 Lifting shaft-   23 Vertical frame guiding element-   24 Container connecting element-   25 Support beam-   26 Battery-   27 Container-handling vehicle according to the invention-   28 Wheel displacement assembly-   30 Guiding pin

The invention claimed is:
 1. A container-handling vehicle for picking upstorage containers from a three-dimensional grid of an underlyingstorage system, comprising: a first set of wheels arranged at oppositesides of a vehicle body, for moving the vehicle along a first directionon the grid; a second set of wheels arranged at opposite sides of thevehicle body, for moving the vehicle along a second direction on thegrid, the second direction being perpendicular to the first direction;and the first set of wheels displaceable in a vertical direction betweena first position, wherein the first set of wheels allow movement of thevehicle along the first direction, and a second position, wherein thesecond set of wheels allow movement of the vehicle along the seconddirection, wherein the vehicle body surrounds a cavity within which atleast a first lifting device and a second lifting device are positionedadjacent to each other, each lifting device is independently controlledand arranged to lift a storage container from the grid and into thecavity, such that a bottom of the storage container is at a level abovethe lowest level of the second set of wheels, and wherein the vehiclecomprises at least one vertical frame guiding element arranged insidethe cavity, the frame guiding element extending between the firstlifting device and the second lifting device and being an integral partof the framework of the vehicle body.
 2. A container-handling vehicleaccording to claim 1, wherein the first lifting device and the secondlifting device are adjacent, such that the container-handling vehiclemay accommodate two adjacent storage containers within the cavity.
 3. Acontainer-handling vehicle according to claim 1, wherein each of thefirst lifting device and the second lifting device is connected to atleast one first rotatable lifting shaft and at least one secondrotatable lifting shaft, respectively.
 4. A container-handling vehicleaccording to claim 1, wherein each of the first lifting device and thesecond lifting device comprises a lifting frame for releasablyconnecting to a container.
 5. An automated storage and retrieval systemcomprising a three-dimensional grid and at least one container-handlingvehicle according to claim 1, wherein the grid comprises multiplestorage columns, in which storage containers may be stored on top of oneanother in vertical stacks, and a port column for receiving andtransporting a storage container to an access station; and the containerhandling vehicle is operated on rails at a top level of the grid forretrieving storage containers from, and storing storage containers in,the storage columns, and for transporting the storage containershorizontally across the grid; wherein the first lifting device and thesecond lifting device are arranged such that they may enter two adjacentstorage columns at the same time.
 6. An automated storage and retrievalsystem according to claim 5, wherein each of the lifting devicescomprises a lifting frame and are arranged such that the respectivelifting frames may enter two adjacent storage columns at the same time.7. An automated storage and retrieval system according to claim 6,wherein the lifting frames of the first lifting device and the secondlifting device are horizontally separated by a distance being largerthan the width of the rails separating two adjacent storage columns. 8.An automated storage and retrieval system according to claim 5, whereinthe container-handling vehicle has a horizontal periphery equal to, orless than, the horizontal periphery of a set of rails surrounding twoadjacent storage columns.
 9. An automated storage and retrieval systemaccording to claim 6, wherein each of the first and second liftingframes comprises container connecting elements for releasable connectionto corresponding lifting frame connecting elements on the storagecontainers, and guiding pins for ensuring a correct positioning of thecontainer connecting elements.
 10. A method of retrieving at least onestorage container from an automated storage and retrieval systemcomprising a three-dimensional grid and at least one container-handlingvehicle, wherein the grid comprises multiple storage columns, in whichstorage containers may be stored on top of one another in verticalstacks, and a port column for receiving and transporting a storagecontainer to an access station; and the container handling vehicle isoperated on rails at a top level of the grid for retrieving storagecontainers from, and storing storage containers in, the storage columns,and for transporting the storage containers horizontally across thegrid; wherein the container-handling vehicle comprises at least a firstlifting device and a second lifting device arranged such that they mayretrieve and/or store a storage container from/in at least two adjacentstorage columns at the same time; and at least one vertical frameguiding element extending between the first lifting device and thesecond lifting device and being an integral part of the framework of thecontainer-handling vehicle, the method comprising: identifying a firststorage container to be retrieved; moving the container-handlingvehicle, such that the first lifting device is centred relative a firststorage column comprising the first storage container; retrieving asecond storage container by the first lifting device, the second storagecontainer arranged in the first storage column at a level above thefirst storage container; moving the container-handling vehicle, suchthat the second lifting device is centred relative the first storagecolumn; retrieving the first storage container by the second liftingdevice; and storing the second storage container in a second storagecolumn.
 11. A method according to claim 10, comprising: moving thecontainer-handling vehicle along a pathway to the port column.
 12. Themethod of claim 10, wherein the second storage column is adjacent to thefirst storage column.
 13. The method of claim 12, wherein the secondstorage container is stored simultaneously with the step of retrievingthe first container.
 14. A method according to claim 10, comprising:returning the second storage container to the first storage column whenthe first storage container has been retrieved.
 15. A method accordingto claim 10, wherein the second storage column is not adjacent to thefirst storage column.
 16. The method of claim 15, wherein the secondstorage column is arranged along the pathway to the port column.